Conveyor belts are used to carry many kinds of materials, ranging from packages to sand and gravel to wet, sticky material that adheres to the belt. If the belt must be stopped for maintenance or replacement, valuable time is lost. Preventing wear of these belts is therefore important.
One way of keeping a belt well maintained is by keeping it clean. Particles can abrade the belt surface or fall into other equipment. If dirt is removed regularly, these problems are lessened.
Often, belt cleaning devices are mounted to clean the belt continuously as it moves. Continuous belt cleaning is important to remove wet, sticky material which does not fall off by itself.
One way belts are cleaned is by mounting motorized roller brushes just below the head pulley around which the belt runs. An example of a brush cleaner is shown at page 7 in the pamphlet of Martin Conveyor Products identified as Form No. 3117-1-86LP. These brushes periodically wear out and need replacement, during which time the conveyor belt must be stopped. Also, the brushes are run by a motor, another component that requires maintenance or may fail.
Another device for cleaning a smooth belt is a series of small rollers which force the belt around slight bends. See, for example, the Conveyor Components Co. Catalog No. C-211 at pages 6 and 7. This bending causes dirt to flake or fall off. These rollers are not effective for all types of material, such as sticky materials which do not fall off easily by themselves.
Another type of cleaner consists of scrapers that are used for removing material, especially sticky material, from a conveyor belt. One type of scraper, called a doctor blade, acts as a knife to cut material off and is mounted to bear against the belt where it wraps around the head pulley. See the above cited Martin Conveyor Products pamphlet at pages 3 and 4. Other scrapers, that act like squeegees, are mounted beneath the belt just after it passes the head pulley. See the Martin Conveyor Products pamphlet at pages 2, 3, and 5, and the pamphlet called Durt Hawg of the Martin Engineering Company, identified as Form No. 3142-785LP. These scrapers are rectangular in cross-section and lean in the direction of the belt's travel.
On both the doctor blade and squeegee types, the scraping edge wears to a rounded shape, tending to let grit pass between the belt and the scraper, which promotes belt wear. When such scrapers wear out, the conveyor must be stopped to replace them. They are often awkward to reach, especially if mounted beneath the belt and pulley.
In the field of conveyor belts generally, it is known to cover the pulley face with lagging. As disclosed in U.S. Pat. No. 3,789,682, one form of lagging is in segments which are held to the pulley by being slid beneath flange-like elements face attached to the face of the pulley. The lagging segments can be replaced without removing the pulley and even without removing the belt from the pulley by replacing segments one at a time when they are positioned out of contact with the belt. As disclosed in the patent, the lagging segments are formed by bonding elastomer to a metal base plate and the metal base plate is held to the pulley face.